Fly ash sampling anti-suck-back device

The utility model provides a fly ash sampling anti-suck-back device which comprises a pipeline connected with a smoke dust sampling device, the pipeline is connected with a sampling nozzle, the sampling nozzle is vertically through, the upper portion of the sampling nozzle is communicated with the pipeline, the lower portion of the sampling nozzle is used for being communicated with a smoke dust pipeline, and an anti-suck-back assembly is arranged in the sampling nozzle. During sampling, under the action of pumping force of a sampling pump, the hollow ball moves backwards along with airflow to the section of the upper portion in the back flushing pipe and is intercepted by the intercepting rod, a gap is reserved between the hollow ball and the back flushing pipe, and the airflow smoothly passes through the gap. When sampling is finished, air flow generated by negative pressure suck-back in the flue blows the hollow ball to the air inlet pipe and blocks the interior of the air inlet pipe, so that the air flow